Blazblue: Cross Tag Battle is $22.79 @ Cdkeys.com for PCDD. This might be the lowest price recorded for the PC version of the game is more than 50% off. The deluxe version is $46. In my opinion I'd go for the vanilla version as its currently on sale right now on steam as part of the EVO sale. Also you can pick up the DLC pack via steam for 10% off.
If your're a fighting game for or even a big fan of Dragon ball fighterz, blazblue series & the guilty gear series this game is absolutely a must buy!
Also: The key on CDKEYS.com is the one that comes with preorder bonuses